Radiation induced esophageal adenocarcinoma in a woman previously treated for breast cancer and renal cell carcinoma

Aberrant p53 Expression in Gastric Biopsies and Resection Specimens Following Neoadjuvant Chemoradiation: A Diagnostic Pitfall

Gastric mucosal biopsies and resections from patients treated with neoadjuvant radiation and/or chemotherapy are frequently encountered. These samples may show histologic features related to therapy including inflammation, ulceration, and epithelial atypia. In some cases, epithelial atypia may be marked, prompting the use of adjunct p53 immunohistochemistry. We examined p53 expression by immunohistochemistry in gastric mucosa following therapy. We evaluated the histology and p53 immunohistochemical expression in gastric mucosa from 57 resections and 3 mucosal biopsies, from 60 patients treated with radiation and/or chemotherapy for gastroesophageal carcinoma (n  =  33) or pancreatic carcinoma (n  =  27). We identified histomorphologic features of therapy-related epithelial changes in 50 of 60 cases (83%). Abnormal p53 expression was present at least focally in nearly half the cases (27 of 60 cases; 45%), all of which showed morphologic evidence of therapy-related epithelial changes. Neuroendocrine cell micronests were present in 37 of 60 cases (62%). Next-generation sequencing (NGS) of foci with therapy-related epithelial changes showing abnormal p53 expression and carcinoma from the same patient was attempted and yielded results in 1 patient. Interestingly, differing TP53 alterations in the patient's adenocarcinoma and in a histologically benign esophageal submucosal gland with therapy-related epithelial changes and abnormal p53 expression were identified. Our results demonstrate that abnormal p53 expression is relatively common in gastric mucosal samples following radiation and/or chemotherapy and suggest that p53 expression should be avoided when distinguishing therapy-related changes from dysplasia or carcinoma. Furthermore, our NGS results raise interesting biological questions, which may warrant further investigation.

Mechanisms of tumor escape from immune system: role of mesenchymal stromal cells

Tumor microenvironment represents the site where the tumor tries to survive and escape from immune system-mediated recognition. Indeed, to proliferate tumor cells can divert the immune response inducing the generation of myeloid derived suppressor cells and regulatory T cells which can limit the efficiency of effector antitumor lymphocytes in eliminating neoplastic cells. Many components of the tumor microenvironment can serve as a double sword for the tumor and the host. Several types of fibroblast-like cells, which herein we define mesenchymal stromal cells (MSC), secrete extracellular matrix components and surrounding the tumor mass can limit the expansion of the tumor. On the other hand, MSC can interfere with the immune recognition of tumor cells producing immunoregulatory cytokines as transforming growth factor (TGF)ß, releasing soluble ligands of the activating receptors expressed on cytolytic effector cells as decoy molecules, affecting the correct interaction among lymphocytes and tumor cells. MSC can also serve as target for the same anti-tumor effector lymphocytes or simply impede the interaction between these lymphocytes and neoplastic cells. Thus, several evidences point out the role of MSC, both in epithelial solid tumors and hematological malignancies, in regulating tumor cell growth and immune response. Herein, we review these evidences and suggest that MSC can be a suitable target for a more efficient anti-tumor therapy.

Connexin-43 regulates p38-mediated cell migration and invasion induced selectively in tumour cells by low doses of γ-radiation in an ERK-1/2-independent manner

Radiotherapy exposes certain regions of solid tumours to low sublethal doses of γ-radiation that may cause secondary malignancies. Therefore, evaluating low-dose-γ-radiation-induced alterations in tumorigenic potential and understanding their mechanisms could help in improving radiotherapy outcome. Limited studies have indicated connexin (Cx) up-regulation by low doses, whereas Cxs are independently shown to alter cell migration in unirradiated cells. We investigated low-dose-γ-radiation-induced alterations in Cx43 expression and cell proliferation/migration/invasion in various tumour cell lines, along with the putative molecular pathways such as p38 and extracellular signal-regulated kinase-1/2 (ERK-1/2)-mitogen-activated protein kinases (MAPKs). Interestingly, a narrow range of low doses (10-20 cGy) enhanced Cx43 expression and also selectively induced glioma cell migration without altering cell proliferation, accompanied by sustained activation of p38 and up-regulation of p21(waf1/cip1), whereas the lowest (5 cGy) dose induced cell proliferation coupled with enhanced p-ERK1/2, proliferating cell nuclear antigen and p-H3 levels without inducing cell migration. Most importantly, low-dose-γ-radiation-induced cell migration and p38 activation was strongly inhibited by knocking down Cx43 expression, thereby demonstrating latter's upstream role, whereas the knock-down had no effect on ERK-1/2 or cell proliferation. Silencing Cx43 caused near-complete inhibition of radiation-induced cell migration/invasion in all tumour cell lines (U87, BMG-1, A549 and HeLa), whereas no cell migration/invasiveness was induced in the γ-irradiated primary VH10 or transformed AA8 fibroblasts. Our study demonstrates for the first time that low-dose γ-radiation induces p38-MAPK mediated cell migration selectively in tumour cells. Further, this effect is regulated by Cx43, which could thus be an important mediator in radiation-induced secondary malignancies and/or metastasis.